/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    DerivedFieldMetaInfo.java
 *    Copyright (C) 2008-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.core.pmml;

import java.io.Serializable;
import java.util.ArrayList;

import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import weka.core.Attribute;
import weka.core.Instances;

public class DerivedFieldMetaInfo extends FieldMetaInfo implements Serializable {

    /** for serialization */
    private static final long serialVersionUID = 875736989396755241L;

    /** display name */
    protected String m_displayName = null;

    /**
     * the list of values (if the field is ordinal) - may be of size zero if none
     * are specified. If none are specified, we may be able to construct this by
     * querying the Expression in this derived field
     */
    protected ArrayList<Value> m_values = new ArrayList<Value>();

    /** the single expression that defines the value of this field */
    protected Expression m_expression;

    public DerivedFieldMetaInfo(Element derivedField, ArrayList<Attribute> fieldDefs, TransformationDictionary transDict) throws Exception {
        super(derivedField);
        // m_fieldName = derivedField.getAttribute("name");
        String displayName = derivedField.getAttribute("displayName");
        if (displayName != null && displayName.length() > 0) {
            m_displayName = displayName;
        }

        // get any values
        NodeList valL = derivedField.getElementsByTagName("Value");
        if (valL.getLength() > 0) {
            for (int i = 0; i < valL.getLength(); i++) {
                Node valueN = valL.item(i);
                if (valueN.getNodeType() == Node.ELEMENT_NODE) {
                    Value v = new Value((Element) valueN);
                    m_values.add(v);
                }
            }
        }

        // now get the expression
        m_expression = Expression.getExpression(derivedField, m_optype, fieldDefs, transDict);
    }

    /**
     * Upadate the field definitions for this derived field
     * 
     * @param fieldDefs the fields as an ArrayList of Attributes
     * @throws Exception if there is a problem setting the field definitions
     */
    public void setFieldDefs(ArrayList<Attribute> fieldDefs) throws Exception {
        m_expression.setFieldDefs(fieldDefs);
    }

    /**
     * Upadate the field definitions for this derived field
     * 
     * @param fields the fields as an Instances object
     * @throws Exception if there is a problem setting the field definitions
     */
    public void setFieldDefs(Instances fields) throws Exception {
        ArrayList<Attribute> tempDefs = new ArrayList<Attribute>();
        for (int i = 0; i < fields.numAttributes(); i++) {
            tempDefs.add(fields.attribute(i));
        }
        setFieldDefs(tempDefs);
    }

    /**
     * Get this derived field as an Attribute.
     * 
     * @return an Attribute for this derived field.
     */
    @Override
    public Attribute getFieldAsAttribute() {
        return m_expression.getOutputDef().copy(m_fieldName);
    }

    /**
     * Get the derived field value for the given incoming vector of values. Incoming
     * values are assumed to be in the same order as the attributes supplied in the
     * field definitions ArrayList used to construct this DerivedField.
     * 
     * If the optype of this derived field is continuous, then a real number is
     * returned. Otherwise, the number returned is the index of the
     * categorical/ordinal value corresponding to result of computing the derived
     * field value.
     * 
     * @param incoming the incoming parameter values
     * @return the result of computing the derived value
     * @throws Exception if there is a problem computing the value
     */
    public double getDerivedValue(double[] incoming) throws Exception {
        return m_expression.getResult(incoming);
    }

    @Override
    public String toString() {
        StringBuffer buff = new StringBuffer();
        buff.append(getFieldAsAttribute() + "\nexpression:\n");
        buff.append(m_expression + "\n");

        return buff.toString();
    }
}
